SITVARIN, Michael I*; IYENGAR, Erika V; CATALDO, Marianne; Muhlenberg College; Muhlenberg College; Muhlenberg College: Functional morphology of flexible periostracal hairs in the marine snail Trichotropis cancellata

Many mollusk shells possess prominent calcified spines that deter predators and assist in stabilization, and a proteinaceous periostracum that inhibits the settlement of boring and encrusting organisms, provides camouflage, or influences water flow around the shell. The marine snail Trichotropis cancellata has flexible periostracal hairs covering the shell, the function of which is unknown. Three crab and two sea star species were presented live snails with the periostracum intact (“hairy shells”) or removed (“smooth shells”), but the hairs did not significantly deter predation. Periostracal hairs deterred settlement by certain organisms (such as barnacles) and promoted settlement by other organisms (such as red algae). We also investigated whether the hairs destabilized the shell during freefall by recording the landing orientation of live hairy and smooth snails. T. cancellata can acquire nutrients both by suspension feeding and kleptoparasitizing (stealing food from) suspension-feeding polychaete worms. To determine whether the hairs influence feeding flow dynamics (critical for suspension feeders), the movement of water around hairy and smooth shells was visualized using calcein and videotape analysis (flow speed = 8.0 cm/s). The effects of the periostracal hairs on fluid flow were complex. Possible ramifications of these alterations on suspension feeding by the snail and worm host will be discussed.